For per-device weight, you can set weight and/or leaf weight.
The problem is, with the recent fix to use BFQ on cgroup v1,
if per-device weights are set, the code tries to set device
weight to blkio.bfq.weight, and the leaf weight to
blkio.leaf_weight_device. The latter file does not exist on
kernels v5.0, meaning one can not set any per-device weights
at all.
The fix is to only set weights if they are non-zero (i.e. set).
The test case will come in a following commit.
Fixes: 6339d8a0dd
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Kir Kolyshkin
30d83d4d2f